The present invention generally relates to methods and apparatuses for producing semiconductor devices, and more particularly to a method and to an apparatus for producing a semiconductor device by transporting a wafer or the like by a transport unit and subjecting the transported wafer or the like to a predetermined process.
When producing a semiconductor device, it is desirable to reduce the generation of particles and to reduce contamination. In addition, when transporting a wafer or the like, it is desirable that substance generated during a process will not become a contaminating substance and affect another process.
Recently, the integration density of semiconductor devices has improved considerably, and LSIs and VLSIs have been reduced to practice. Due to the high integration density resulting from such an improvement, a minimum line width of a wiring pattern, for example, has been reduced to the .mu.m order. In order to form a fine pattern, it is necessary to establish a technique for forming the fine pattern. For this reason, the wavelength of exposure light used in exposure apparatuses is being shifted to the short wavelengths in order to cope with the formation of the fine pattern. For example, the light source of the exposure apparatus outputs a g-line having a wavelength of 436 nm when making a 1M DRAM, and outputs an i-line having a wavelength of 365 nm when making a DRAM having a memory capacity in the range of 16M to 64M. In addition, it may be regarded that a KrF excimer laser which outputs a light having a wavelength of 248 nm will be used primarily when making a DRAM having a memory capacity in the range of 64M (shrink version) to 256M, and an ArF excimer laser which outputs a light having a wavelength of 193 nm will be used primarily when making a DRAM having a memory capacity greater than 256M.
According to the exposure method which uses the excimer laser, it is presently regarded that the resist used for the pattern transfer will be a chemically amplified resist, when the sensitivity and transparency are taken into consideration. However, as is known from S. MacDonald et al., "Airborne Chemical Contamination of a Chemically Amplified Resist", Proc. SPIE Vol. 1466, Advances in Resist Technology and Processing VIII, 1991, pp. 2-12, the performance of the chemically amplified resist greatly deteriorates due to the existence of even an extremely small amount of amine system substance in the atmosphere, including ammonia system substance. Accordingly, if the amine system substance exists, it will be difficult to carry out a satisfactory pattern formation using the chemically amplified resist.
Therefore, in the semiconductor device production of the next generation using the chemically amplified resist, it will become necessary to positively prevent contamination in the resist coating process and the developing process by even an extremely small amount of amine system substance.
Presently, as a preparation process which is carried out when coating the resist, there is a known method which processes the substrate surface by a hydrophobic processing agent such as hexamethyl-disilazane (HMDS), in order to prevent the developing agent from spreading to the interface between the resist and the substrate and causing separation. However, ammonia will be generated when this HMDS is hydrolyzed. In addition, an amine system gas is generated from an alkaline solution which is used for the developing agent. For this reason, the contamination sources of the amine system substance which must be eliminated when using the chemically amplified resist, exist from the substrate preparation process to the developing process.
According to the conventional semiconductor device producing apparatus, the same transport unit is used to transport the substrate for the resist coating process and the developing process, for example. In other words, the transport unit used for each process is not used exclusively for the process, and one transport unit is used in common for a plurality of processes. For this reason, there was a problem in that contaminating substance or the like originating from for example the HMDS gas adhered to the transport unit during one process will be carried to another process when the transport unit transports the substrate. In addition, since one transport unit is used in common for a plurality of processes, there was also a problem in that the contaminating substances adhered to the transport unit during one or a plurality of processes will be carried to other processes.